| Abstract: | Isozyme analyses have been carried out to investigate the sites of integration of the herpes simplex type 2 (HSV-2) thymidine kinase (TK) gene in biochemically transformed human [HeLa(BU25)/HSV-2–6 Cl 4] cells. Extracts were prepared from He La (BU25)/HSV-2–6 Cl 4 cells and from human—mouse somatic cell hybrids, which were obtained by fusing the biochemically transformed human cells with TK-deficient mouse [LM(TK?)] cells, and were assayed for 26 isozymes representing markers for 20 human chromosomes. The isozyme analyses were generally consistent with previous karyotype studies, which revealed that the HSV-2 TK gene was associated with an isochromosome, designated M13, formed from the short arm of human X chromosome in human—mouse hybrid lines HL/2 to HL/7, but with human chromosome 17 containing a trans-location on the short arm in hybrid line HL/1 and its TK-positive subclones. The isozyme analyses also indicated that the translocation on the short arm of human chromosome 17 in hybrid line HL/1 was probably derived from human chromosome 21. Hybrid line HL/1 and its TK-positive subclones expressed a human—mouse heteropolymeric form of superoxide dismutase, a marker for human chromosome 21, but bromodeoxyuridine-resistant, TK-negative subclones of HL/1, and hybrid lines HL/3 to HL/6, which did not contain the modified chromosome 17, failed to express the human—mouse heteropolymeric form of superoxide dismutase. The human galactokinase isozyme, which is coded by a gene mapping close to the cytosol TK gene on human chromosome 17, was detected in extracts of TK-positive HeLa S3, TK-deficient HeLa(BU25), and biochemically transformed HeLa(BU25)/HSV-2–6 Cl 4 cells, but not in extracts prepared from human—mouse hybrid line HL/1 and its subclones. These observations suggest that the gene for human galactokinase was either deleted or inactivated in HL/1 and its subclones, perhaps as a result of the translocation to chromosome 17. |
